Acetylene container filler and methods



rates This invention relates to containers for holding dissolved acetylene, which containers are provided with a porous absorbent material or filler. More particularly, the invention is directed to an improved highly porous filler for acetylene containers together with a method of manu facturlng such a filler and a method of filling acetylene containers with such improved filler material.

This application is a division of prior application Serial No. 564,360, filed February 9, 1956, for Acetylene Container Filler and Methods, now Patent No. 2,944,911.

It is well known that acetylene gas, even in very small amounts, may become violently unstable at pressures in excess of 15 p.s.i. and almost with certainty above 50 p.s.i. This condition is substantially overcome by dissolving the acetylene in acetone which will dissolve as much as 6 times its own weight of acetylene. Pressures up to 300 p.s.i. or more of dissolved gas may be obtained in this manner if the acetone container is filled with a highly porous material, the individual pores of which are minute. The material must be such however that it will not settle, shrink or distintegratc to leave voids within which acetylene gas under pressure may collect and become unstable. In other words, in addition to high porosity, it must have relatively high compressive strength and dimensional stability.

Heretofore a large number of materials have been proposed for use as fillers for acetylene containers. These among others have included balsa wood, Kapoc, kieselguhr, charcoal and asbestos. Such fillers, although sound in nature, were limited to a porosity in the neighborhood of 75%. More recently a substantially monolithic filler for acetylene cylinders has been proposed, having a porosity of between 80% and 86%. Such a filler comprises the calcium silicate product obtainable by reaction between calcium hydrate and a material consisting essentially of silica, such as sand. This form of filler, although good in such qualities as strength and porosity, exhibits substantial shrinkage which creates voids between it and its container, and hence it lacks the requisite dimensional stability required for complete satisfaction of the intended purpose.

In the present invention, by suitable combination and proportion of ingredients, together with a predetermined method of compounding these, a highly desirable, dimensionally stable, high porosity, low volume and high compressive strength filler has been obtained, the overall porosity of which is in the neighborhood of 90% to 92%. Moreover, the invention further comprises a method for obtaining the complete filling of acetylene containers with this material.

It is accordingly, the principal object of this invention to provide a filler material of high porosity, low volume and substantial compressive strength capable of completely filling acetylene containers.

A further object of this invention, in keeping with the foregoing object, is to provide a filler material for acetylene containers of the type comprising hydrated calcium meta-silicate, reinforced with charcoal and asbestos.

Another object of this invention is to provide a method for compounding the acetylene container filler material set forth in the foregoing objects.

2 Claims.

atent i iQQ Still another object of this invention is to provide a method for completely filling acetylene containers with the materials referred to in the foregoing objects, in a rapid and eflicient manner.

These and additional objects and advantages of the invention will become apparent as the following description proceeds.

The preparation and composition of the improved acetylene container filler according to this invention comprises an initial pre-treatment of charcoal and lime in the following marmer. Porous charcoal, preferably screened to pass through a /2 inch mesh, is soaked under water for at least 12 hours. in this period of time the small sized pieces of charcoal absorb water to capacity.

Pulverized lime (any high calcium commercially available pulverized lime is acceptable) is hydrated with water to obtain a slurry comprising about 20% by weight of the calcium oxide.

Sufiicient additional water to make the entire water-tosolids ratio equal to approximately 3.8 is then placed in a mixing vessel, into which is charged fibrous asbestos. The fibrous asbestos and water are mixed until all visible air bubbles have disappeared.

The pro-soaked charcoal is then added to the asbestos water slurry and dispersed by agitation.

At this point finely divided silicon dioxide, preferably in the form of diatomaceous earth, is then added to the asbestos-charcoal-Water slurry, at such a rate as to minimize agglomeration or the formation of lumps. Thereafter mixing should continue for a period of around 15 to 30 minutes. The silicon dioxide is added in an amount equal to twice the weight of the lime originally hydrated.

The hydrated lime mixture is then charged into this slurry and mixing is continued for a period of approximately 15 minutes or until the entire mass is homogeneous. At this point, the filler slurry may be removed from the mixer and is ready for charging into the acetylene containers.

The following formula has been found to be preferable to obtain a porosity in the neighborhood of 92%:

Water to solids ratio by Weight 3.8 Silicon dioxide to lime weight ratio 2.0 Asbestos in percent of solids by Weight 25% Charcoal in percent of solids by weight 20% It has been found that variations may be made in this preferred formula, but these should not exceed about 20% as to each ingredient.

Fillers having a porosity of between 88% and 90% have been obtained by the following formula:

Water to solids ratio 3.5 Silicon dioxide to lime weight ratio 2.0 Asbestos in percent of solids by Weight 20% Charcoal in percent of solids by weight 15% Other formulas which have been found to be acceptable but not to the degree of the preferred formula, principally because of lower poroslties and less crushing strength are:

Silicon dioxide to lime weight ratio 1.61 to 2.47 Asbestos in percent solids by weight 20% to 30% Charcoal in percent solids by weight 15% to 30% Water to solids ratio by weight 3- to 4.5

It should be noted however that any substantial increases in the water to solids ratio by weight and in the silicon dioxide to lime ratio greater than those indicated result in shrinkages in excess of those that can be compensated for by the charcoal, and this restricts their value as acetylene container fillers.

The completed filler slurry as described is placed in a hopper from which it is introduced into empty commercial acetylene container shells. It is preferable that one of the top fuse plugs of each of the shells be removed and a vacuum line attached. The filling is preferably carried out with a vacuum maintained at about 25 inches. of mercury. When the containers are about half filled, the filling should be stopped and the cylinder vibrated or jarred for about 30 to 60 seconds. The filling is then continued until no additional slurry will flow into the containers. The containers are then again vibrated for 30 to 60 seconds, after which they are disconnected from the filling apparatus, all holes plugged, and permitted to settle for a period from 12 to 18 hours. After the filled containers have settled, overnight for example, they are again attached to the vibrating apparatus and jarred for another period of 30 to 60 seconds. Filler material of the same batch, for example from which the containers were filled the previous day, is then introduced to fillany space remaining in the shell due to settling or tamping of the filler. The top plug is then replaced and the cylinder is again vibrated for about 30 to 60 seconds. It is reopened and additional filler slurry is again introduced if necessary. This vibrating and filling is repeated until no settling is produced on additional vibration. It has been found generally that about three of such cycles are usually necessary to fill the containers completely. The containers are then removed from the vibrating apparatus and are in condition to be indurated.

In order for the proper chemical recation to take place within the tiller slurry in a reasonable length of time, heat is applied to the container while the loss of water is prevented. It has been found that this induration should be performed promptly after the final filling cycle. Since water expands in this heating process, it is necessary to provide the containers individually with hydraulic expansion heads. The pressure increase produced by the expanding water is compensated for by the expansion heads which increase the internal volume of the container when acted upon by the expanding water. This prevents possible rupture of the container and permits the use of lighter weight containers having structurally Weaker walls than would be otherwise possible. Upon cooling the container, the pressure decreases and the head returns to its initial position and restores the initial internal volume of the container.

A suitable oven in which the filled containers are placed is brought to a temperature in the range of from 350 to 375 degrees Fahrenheit and is maintained within that range during the entire treatment. Induration should continue for a period of approximately 15 to 16 hours after the oven has reached 350 degrees F.

After the induration period has been completed, the filler is dried under vacuum.

After the containers have cooled, each container is then inspected to determine porosity and density, after which it is charged with acetone in accordance with Interstate Commerce Commission specifications, and then filled with acetylene.

It will be apparent to those skilled in the art that certain modifications in the formulation of this filler material, as well as in the process of compounding and preparing it,

and the process of preparing and filling the containers with the filler material after it has been compounded, may be made without departing from the spirit of this invention, and such modifications are intended to be included within the scope of the invention as defined by the appended claims.

We claim:

1. Method of preparing acetylene containers with a dimensionally stable filler composition comprising an aqueous slurried mixture of charcoal and fibrous abestos dispersed and set in the product of silica and lime reacted under pressure and in the presence of water and heat, in which the proportion by weight of silica to lime is from about 1.61 to about 2.47, comprising the steps of drawing the prepared slurried composition into the containers under a vacuum pressure until about half full, vibrating the containers for a short time, completing the filling of the containers with the composition under said vacuum pressure and again vibrating the containers for a short time, closing the containers and permitting the composition to settle for at least twelve hours, refilling the settled space in said containers with said composition and vibrating the containers briefiy in oneor more cycles, indurating the material in the containers in an oven under heat and pressure while retaining the water in the containers, and driving oif excess moisture from the containers.

2. A method of preparing acetylene containers with dimensionally stable filler composition consisting essentially of a slurry of charcoal and fibrous asbestos dispersed and set in a silica-lime product, according to the following formula:

Silica to limeproportion by weight 1.61 to 2.47 Water to solids proportion by weight 3 to 4.5 Asbestos in percent solids by weight 20% to 30% Charcoal in percent of solids by weight--- 15% to 30% comprising the steps of filling the containers with the prepared slurried composition, then vibrating the so-filled containers for a short time, then filling the containers with further composition, subjecting the containers to further vibratory action for a short time, then further filling the cylinders with composition, at least certain of said filling and vibrating steps being carried out while the cylinders are under vacuum pressure, then indurating the material in the containers in an oven under heat and pressure, the applied heat being such as to raise the temperature Within the heart of the core of material within the cylinders to a temperature on the order of about 350 to 375 degrees Fahrenheit and for a period of about 16 hours, and then driving ofi the excess moisture from the containers while under vacuum pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,127,401 Gilligan Aug. 16, 1938 2,538,441 Carter Jan. 16, 1951 2,595,262 Hood May 6, 1952 2,766,131 Seipt Oct. 9, 1956 2,883,040 Pater a a1 Apr. 21, 1959 

1. METHOD OF PREPARING ACETYLENE CONTAINERS WITH A DIMENSIONALLY STABLE FILLER COMPOSITION COMPRISING AN AQUEOUS SLURRIED MIXTURE OF CHARCOAL AND FIBROUS ABESTOS DISPERSED AND SET IN THE PRODUCT OF SILICA AND LIME REACTED UNDER PRESSURE AND IN THE PRESENCE OF WATER AND HEAT, IN WHICH THE PROPORTION BY WEIGHT OF SILICA TO LIME IS FROM ABOUT 1.61 TO ABOUT 2.47, COMPRISING THE STEPS OF DRAWING THE PREPARED SLURRIED COMPOSITION INTO THE CONTAINERS UNDER A VACUUM PRESSURE UNTIL ABOUT HALF FULL, VIBRATING THE CONTANERS FOR A SHORT TIME, COMPLETING THE FILLING OF THE CONTAINERS WITH THE COMPOSITION UNDER SAID VACUUM PRESSURE AND AGAIN VIBRATING THE CONTAINERS FOR A SHORT TIME, CLOSING THE CONTAINERS AND PERMITTING THE COMPOSITION TO SETTLE FOR AT LEAST TWELVE HOURS, REFILLING THE SETTLED SPACE IN SAID CONTANERS WITH SAID COMPOSITION AND VIBRATING ING THE CONTAINERS BRIEFLY IN ONE OR MORE CYCLES, INDURATING THE MATERIAL IN THE CONTANERS IN AN OVEN UNDER HEAT AND PRESSURE WHILE RETAINING THE WATER IN THE CONTAINERS, AND DRIVING OFF EXCESS MOISTURE FROM THE CONTAINERS. 